Grand piano action



@ fii; 27, 1931. c. TRINKLE GRAND PIANO ACTION I Filed Nov. 24 1930 INVEN TOR B W/WZ W wzzg.

ATTORNEY Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE CARL TRINKLE, OF CINCINNATI, OHIO, ASSIGNOR TO THE BALDWIN COMPANY, OF CINCINNATI, OHIO GRAND PIANO ACTION Application filed November 24, 1930.

Many improvements have been attempted to obtain an easy touch of the key and a fast acceleration of the piano hammer in grand piano actions, but these improvements have 5 been attempted at certain points that did not give the desired result to the artist. In the present invention a cam acts directly on the hammer shank, giving an easy touch and acceleration of the movement of the hammer that enables the average performer to produce fortissimo effects that are usually possible only to the artist of great strength.

In the drawings Fig. 1 is a side view of the action and key when at rest and Fig. 2 is a view from the same angle when the key is down and the jack has moved forward into the depression of the underside of the cam and the hammer is engaged by the backcheck.

A grand piano action has a key 1 with a capstan 2 that supports a wippen 3. Pivoted on the wippen 3 is a cam lever 4 that is operated by a jack 5 that is pivoted at the forward end of the wippen 3. A spring 6 is fastened in the cam lever A and bears down on a projection at the rear of the jack 5 imparting a lifting effect on the cam lever 4 and causing the stop button 7 to bear against the stop 8 on the wippen 3.

The hammer 9 is attached to the hammer shank 10 which is pivoted to a flange 11 that is screwed to a rail 12. A back-check 13 is attached at the rear of the key 1 at a position to engage the heel of the hammer 9 in the usual manner. A let-off button 14 is screwed to the under face of the rail 12 in such a position as to engage the forward end of the jack 5 at the last part of the stroke.

When the key 1 is depressed the capstan 2 raises the wippen lever 3. At this time the jack 5 is resting under theknuckle portion of the cam lever 4 causing it to roll evenly under the hammer shank 10 thereby raising the hammer 9 with acceleration toward the string 15, as the contact point of the cam lever 4 approaches the pivot pin where the hammer shank is attached to the flange 11.

At the last more or less, of the key stroke, the forward end of the jack 5 comes in contact with the let-off button 14 causing Serial No. 497,795.

the top of the jack to move out from under the knuckle portion of the cam lever 4 just before the hammer 9 strikes the string 15. As the jack moves free from the knuckle portion of the cam lever 4 the cam lever drops down with its padded recessed portion resting on the head of the jack 5 letting the hammer 9 drop back until its heel engages the back-check 13.

In normal operation the hammer 9 moves with sufficient inertia to cause it to continue to rise after the jack is tripped and to strike the string 15 before dropping back on the back-check 13. When the key 1 starts to rise as for repetition, the ack 5 is pulled back under the knuckle portion of the cam lever A by the spring 6 while the Weight of the hammer 9 is carried by the back-check 13.

It is possible to build a cam shaped piece on the bottom of the hammer shank 10 and also possible to make part of the cam action on the hammer shank 10 and part on the cam lever 4: and obtain the same results. This cam lever A can also be controlled by a broken or jointed jack which would be pivoted both on the wippen 3 and the cam lever A but for simplicity the present jack 5 is preferable.

What I claim as my invention is:

1. In a grand piano action, a hammer head swung on a straight hammer shank, a cam lever, controlled by a jack, operating the straight hammer shank and means for causing the jack to escape under the cam lever, and the hammer head to return part way to starting position.

2. In a grand piano action, a hammer head swung on a straight hammer shank, a cam lever adapted to operate the hammer shank and means for the cam lever and straight hammer shank to partially return to starting position.

3. In a grand piano action, a hammer head swung on a straight hammer shank, a cam lever controlled by a jack, operating the straight hammer shank and means for causing the ack to escape under the cam lever.

CARL TRINKLE. 

